In general, a patterned transparent conducting film is widely used in an electronic device such as a touch panel, a solar cell, or an organic light-emitting diode device. Ag or an Ag alloy obtained by adding another element to Ag is a material having excellent electrical conductivity, and in a case where a thin film is formed using Ag or an Ag alloy, high transmittance can be obtained. Therefore, application of Ag or an Ag alloy to a transparent conducting film in the above electronic devices has been expected (refer to PTL 1).
In addition, in the fields of heat ray cutting, a display device, and the like, an optical functional film is used. As such an optical functional film, a transparent laminated film so-called a multi-layer film type is known, in which a high refractive index thin film formed of a metal oxide and a metal thin film are alternately laminated on a single surface of a transparent polymer film. As a material of the metal thin film of the optical functional film, Ag or an Ag alloy is used (refer to PTL 2).
However, Ag or an Ag alloy has a problem in that deterioration in properties and a change (for example, speckles) in the external appearance of a film formed of Ag or an Ag alloy are likely to occur due to corrosion caused by humidity, sulfur, and the like in environment during the manufacturing process and during usage. In a case where a film formed of Ag or an Ag alloy has a thickness (15 nm or less) of a semi-transparent film or the like, the above phenomenon appears more significantly, and there is a problem in that the formation of speckles may occur due to aggregation which may occur by particles being deposited on a surface of the film.
PTL 3 and PTL 4 disclose an Ag alloy film in which environment resistance is improved.
PTL 3 discloses an Ag alloy film obtained by adding a noble metal such as platinum, palladium, gold, rhodium, ruthenium, or iridium to Ag.
In addition, PTL 4 discloses an Ag alloy film including Bi and at least one selected from Zn, Al, Ga, In, Si, Ge, and Sn.